In the application of insulation displacement connectors (IDC's) in the communications industry, it is often desirable to be able to connect two wires into a single contact. Many methods of achieving this have been devised. Some consist of a single planar metal contact with two slots, each to accommodate one wire, but more sophisticated designs which can connect two wires in a single insulation displacement slot have generally proved more simple in use, and generally therefore more commercially acceptable.
One of the most used connectors is made by Krone GmbH of Berlin, Germany, and sold as the LSA PLUS connector. The construction is described in DE 2,725,551 and uses a planar metallic contact constrained within a plastic connector body to remain at 45.degree. to the wire to be terminated. In use, when two wires are inserted, the contact, which is constrained both at the top and the bottom of the slot, will flex and deform symmetrically around two wires of the same size. Because of the symmetrical nature of the contact's mechanics, this system has the disadvantage that it will only work satisfactorily with two wires of the same conductor size. It has the further disadvantage that it requires the wire to be securely gripped within the connector body to overcome the mechanical forces tending to rotate the conductor into mechanical equilibrium at 90.degree. to the IDC contact.
Another form of IDC capable of terminating two wires is described in U.S. Pat. No. 4,141,618. This contact is cylindrical and has an axial slot in which wires may be inserted. It is mechanically superior to the design disclosed in DE 2,725,551, because it is capable of functioning without either the wire or the contact having to be constrained in any state of tension or torsion. However, it has the disadvantages that it requires a relatively large amount of material to manufacture the contact, and it is not possible to make connection to a wire without cutting the wire; thus, it is not possible to have a pass-through connection, which is often desirable in communications wiring. For these reasons, despite its excellent connection characteristics, it has been a relatively unsuccessful contact in the industry.
Another form of contact can be made, by the use of two IDC blades each at 45.degree. to the wire. This is described first in GB 1,361,127 with most recent techniques being disclosed in U.S. Pat. No. 5,044,979, and WO 91/22941. This contact has the advantage of incorporating the mechanical equilibrium of the slotted cylinder arrangement, with the feed-through wiring capability of the 45.degree. contact of DE 2,725,551. It has been commercially manufactured by the present applicant for several years, and has proved functionally reliable in the termination of two wires of the same conductor size. The design attempts to replicate the function of the slotted cylinder contact, but uses flat blades, and hence a simplified manufacturing process. It has the disadvantages of requiring a very precise mechanical restraint system in the plastic body of the connector to restrain the contact blades from rotation, and like the 45.degree. planar contact, can only work with two wires of the same conductor size because it is constrained to deform symmetrically around the conductors by its mechanical arrangement.
It is desirable to increase the functionality of IDC's in the telecommunications industry. It would be particularly desirable to produce a contact which can either terminate more than two wires of the same size, or two wires of slightly different conductor size, such as is possible with the contacts disclosed in U.S. Pat. No. 4,141,618, but which does not suffer from the disadvantages associated with split cylinder type contacts discussed previously.
The invention resides generally in the provision of a contact which is generally arcuate. More specifically there is provided a contact for an insulation displacement connector comprising a first contact portion for receiving one or more wires and a second contact portion, the first contact portion having a central longitudinal slot defining a pair of contact tines, and being of generally arcuate shape.
The invention also resides in an insulation displacement connector housing a plurality of insulation displacement contacts as defined.
Preferably the first contact portion is semi-elliptical and symmetrical about the longitudinal slot. One preferred construction is semi-circular. The arcuate construction may have parallel end portions to assist retention in a housing.
The use of an arcuate contact portion overcomes the disadvantages of the split cylinder design in that it has a feed through capacity. However it retains the advantage that two wires of different thicknesses may be retained at the same time. Moreover it avoids the disadvantage of the V shaped contact as precise mechanical restraint in the plastic housing of the connector is not necessary.